Concrete presents many unique challenges in terms of its protection. Concrete is a relatively porous substrate that is inherently alkaline in nature. As such, it is highly reactive to acids and is easily, unintentionally stained or otherwise soiled. Likewise, concrete is relatively soft and prone to wear and deterioration. Coatings are often used to protect concrete from wear, unintentional staining or soiling and acid etching. These coatings must be somewhat tolerant to the alkaline nature of concrete, and as a result are typically more difficult to remove than traditional styrene/acrylate based floor coatings. Furthermore, intentionally colored concrete flooring presents a unique challenge from the perspective of coating removal compositions in that traditional compositions that are effective for coating removal may damage or discolor such flooring. This often results in permanent, unsightly damage and/or necessitates the recoloring of the concrete at significant cost. This is largely the result of the highly alkaline nature of the coating removal compositions and the presence of relatively strong chelating agents, such as EDTA, etc., attacking the metal based colorant component of the intentionally colored concrete.
It, has been common to treat such concrete surfaces with semi-permanent coatings, such as those utilizing epoxy or urethane technologies. These coating systems suffer from their lack of removability and repairability. Likewise, they often require highly skilled or trained installers due to the sensitive nature of the application and the potentially hazardous profile of the chemistry involved. Such semi-permanent coatings are also expensive. Unfortunately, use of conventional removable coatings, such as acrylic based coatings, which are more cost effective, less labor intensive and utilize less hazardous chemistry has not heretofore provided satisfactory results because of the need for repeated, regular removal/stripping and reapplication. Such repeated removal or stripping with traditional strippers results in further, more extensive damage to the color component of the concrete flooring substrate because of more frequent use. Thus, there are a significant number of limitations with prior art coatings. Additionally the results are often unsatisfactory, in particular for intentionally colored concrete flooring, wherein the color is significantly diminished, discolored or entirely removed.
Previously, removal of coatings from decorative concrete substrates has been complicated due to the sensitive nature of the substrate to traditional chemistries used in coating removal compositions. Currently, coating removal compositions for intentionally colored or stained, decorative concrete are based on solvent systems that resemble heavy duty paint stripping products. These products prevent the displacement of metal ions that give the concrete its colorful look. The result of not using a product that is safe for color is gray concrete. Typically, such prior art strippers “safe” for colored concrete contain a blend of chemicals such as; N-methyl pyrolidone, methyl ethyl ketone, alkylene carbonates, dibasic ester mixtures, etc. These chemistries are undesirable for larger areas of removal, are difficult to work with, and potentially harmful if contact or inhalation has occurred. Clearly, a significant number of drawbacks are associated with prior art colored concrete coating strippers.
In summary, a considerable number of deficiencies exist in the art relating to the coating of concrete substrates and the subsequent removal of those coatings. This is particularly true in the case of intentionally colored, decorative concretes.
Accordingly, it is an object of the present invention to provide a coating removal composition wherein said composition provides good performance on the removal of coatings while reducing the damage such compositions impart to intentionally dyed, stained or pigmented substrates, such as decorative concrete. In particular, there is a need for an improved coating removal composition, which overcomes the shortcomings of the compositions of the prior art.